Fenway Park

This one's sort of a no-brainer if you're a baseball fanatic. The Red Sox have been playing in this venerable stadium since it was built in 1912. So just about every modern day legend from the American League has played here. And it's got all kinds of quirks that almost no modern stadiums have, such as the Green Monster and "the triangle." Getting a ticket to a game can be tough, but they do offer tours throughout the year. Admission is much cheaper at $12 per adult.